GB1434777A - Character representation systems - Google Patents

Abstract

1434777 Cathode-ray tube displays SIEMENS AG 18 Dec 1973 [10 Jan 1973] 58612/73 Heading H4T In a cathode-ray tube display system in which a data source, e.g. a data processor or a keyboard, supplies character data to an image repetition store supplying an output to a character generator from which, via a digitalto-analogue converter, beam deflection signals to trace the characters are supplied to the tube, the data source is additionally operable to supply tabular data which is indicative of the position on the tube screen at which a tabulator mark is to be displayed, the character generator then producing the signals necessary to trace such mark at the required position. As shown in Fig. 2, the screen of the tube is deemed to be divided into a plurality of zones arranged in rows Z1 to Z81 and in columns S1 to S16 each zone corresponding to a storage location in the image repetition store. In operation, when character date is to be displayed, a "printmark" S.M. is entered into the storage location corresponding to the position at which a character is to be displayed, the character data is stored in the same location and the "print mark" is automatically shifted (to the right) by one zone. Thus each character is displayed in any zone in which the print mark was previously displayed. For the display of tabular marks the "print mark" is set up in the required position and the tabulator mark HT is displayed as in the case of the display of characters, when a "tabulator set" key is operated. The tabulator marks may be displayed in any zone in rows Z1, Z2 or Z16, the marks moving up or down the screen in accordance with a "rolling-page" type display, i.e. progressively down from row Z1 to row Z16 or progressively up from row Z16 to row Z1. When the marks are initially displayed in row Z1 or reach this row as a result of the "rolling- page" operation, they are displayed permanently, i.e. for the duration of any one operation. When rapid display of characters between tabular marks is required operation of a "tabulator-jump" key causes the display to process to and then stop at a tabulator mark. Other key facilities provided include "erase tabulator mark", "erase tabulator row" and "erase image" (i.e. the characters) without erasure of the tabulator marks. Instead of displaying the tabulator mark in separate zones it may be displayed in the same zone as the character (Fig. 5). The whole operation is described with reference to logic circuitry, Figs. 1, 3, 4, 6 and 7 (none shown).